CN101430566A

CN101430566A - Method for controlling etching deviation

Info

Publication number: CN101430566A
Application number: CNA2007100480009A
Authority: CN
Inventors: 罗大杰
Original assignee: Semiconductor Manufacturing International Shanghai Corp
Current assignee: Semiconductor Manufacturing International Shanghai Corp
Priority date: 2007-11-08
Filing date: 2007-11-08
Publication date: 2009-05-13
Anticipated expiration: 2027-11-08
Also published as: CN101430566B

Abstract

The invention provides a method for controlling etching deviation. The etching deviation is the difference value between the size ADI CD of dimension of a specific picture after photoetching and the size AEI CD of dimension of a dielectric layer after etching; wherein, the method comprises two steps of establishing a database and automatic control; firstly, databases of different etching deviations which different exposure focuses are corresponding to are established; and then the step of the automatic control is carried out in the actual technique; the automatic control step comprises the following substeps: a1. The measured values of the ADI CD and the AEI CD are acquired; and then the corresponding etching deviation is acquired; a2. The databases are searched so as to find out the exposure focuses which are best matched with the etching deviation; a3. The current exposure focuses are set as the searched best match exposure focuses. The method can effectively overcome defects caused by drift in the using process, can monitor the etching deviation in real time, and adjusts exposure focuses in real time according to the etching deviation.

Description

The method of control etch bias

Technical field

The present invention relates to semiconductor technology, relate in particular to a kind of method of controlling etch bias.

Background technology

The size of special pattern size characterizes by ADI (After Develop inspection) CD (CriticalDimension) after the photoetching, and AEI (After ETCH inspection) CD is the size of dielectric layer size after the etching.It is etch bias (Etch bias) that the difference of ADI CD and AEI CD obtains.

Most important two parameters of exposing are exposure energy (Energy) and focal length (Focus).If it is bad that energy and focal length are adjusted, just the figure of resolution that can not obtain requiring and requirement size shows that mainly the ADI CD of figure exceeds the scope of requirement, thereby causes etch bias to exceed critical field.Exposure energy is mainly regulated the width of figure, but can not change the angle of sidewall, promptly can not change the shape of figure after the photoetching, just changes the size of figure.

In existing technology, configure exposure energy and focal length usually, begin to carry out photoetching process and etch process then, measure etch bias then.Yet,, thereby cause etch bias to exceed ideal range because the focal length of exposure bench can drift about in practical operation in the photoetching process.Usually, AEI CD changed after the variation of the size ADI CD of the figure after the photoetching can directly cause etching.Whether qualified the size of AEI CD be product benchmark, because its size has determined the travelling speed of device.After product began to produce in batches, ADI/AEI CD fixed.One of them way commonly used is to adjust AEI CD.Etch process is responsive especially to the character of photoresist, in etching process, earlier photoresist ADI CD is measured, by plasma etching photoresist is repaired (trimming) then, its size is adjusted to be satisfied in the scope that AEICD requires after the etching.According to the measurement result of photoresist ADI CD before the etching, measurement in real time can be adjusted timely to etching period, thereby the ADI CD that photoetching process is produced compensates.Thisly adjust the process more complicated of graphics shape after the etching by adjusting etched parameter, need accurate proportioning and adjusting, for example need to regulate etching gas concentration and proportioning, etching period etc., and be easy to influence the electrical parameter of product, and change etching parameter, not only can have influence on CD, also can have influence on the shape (profile) of etched figure, might have influence on the performance of device.

Summary of the invention

The object of the present invention is to provide a kind of method of controlling etch bias, it can control etch bias in real time at ideal range.

For achieving the above object, the invention provides a kind of method of controlling etch bias, etch bias is the difference of the big or small AEI CD of dielectric layer size after the big or small ADI CD of special pattern size after the photoetching and the etching; Wherein, this method comprises sets up database steps and automatic controlled step, at first set up the database of the different etch bias of different exposure focal length correspondences, can carry out the step of automatic control then in actual process, this automatic controlled step comprises following substep:

A1. obtain the measured value of ADI CD and the measured value of AEI CD earlier, obtain corresponding etch bias then;

A2. search database finds the exposure focal length that mates most with this etch bias;

A3. existing exposure focal length is set at the exposure focal length that mates most that searches.

The described step of setting up database comprises following substep:

B1. at first fixedly exposure energy is constant, and setting the exposure focal length is different numerical value, carries out the measured value that photoetching process is obtained ADI CD afterwards again;

B2. carry out etch process then, and obtain AEI CD measured value;

B3. obtain corresponding etch bias according to ADI CD measured value and AEI CD measured value;

B4. repeat above-mentioned steps b1, b2 and b3, the database of the different etch bias of the different exposure of foundation focal length correspondences.

Adopt the advanced technologies server to obtain measured value and the ADI CD measured value of ADI CD, and calculate etch bias, and find the exposure focal length that mates most according to the etch bias search database.

Exposure bench is connected with the advanced technologies server, and the advanced technologies service search feeds back to exposure bench to the exposure focal length that mates most, and it is the exposure focal length that mates most that searches that exposure bench can be set its exposure focal length.

Compared with prior art, the present invention effectively overcomes because after exposure bench operation a period of time, the drift of exposure focal length causes final etch bias to exceed this defective of ideal range.The present invention is the monitoring etching deviation in real time, adjusts the exposure focal length in real time according to etch bias.Simple and the realization easily of the method for this control etch bias effectively provides production efficiency, and has reduced production cost.

Description of drawings

To the description of one embodiment of the invention, can further understand purpose, specific structural features and the advantage of its invention by following in conjunction with its accompanying drawing.Wherein, accompanying drawing is:

For a change the expose variation synoptic diagram of figure after the focal length photoetching of Fig. 1.

Fig. 2 controls the synoptic diagram of the method for etch bias for the present invention.

Fig. 3 is the synoptic diagram of corresponding relation between exposure focal length and the etch bias.

Embodiment

For a change the expose variation synoptic diagram of figure after the focal length photoetching of Fig. 1.Change the inclination angle that the exposure focal length can change figure after the photoetching.Based on this principle, the invention provides a kind of method of controlling etch bias, this method comprises sets up database steps and automatic controlled step:

About setting up database steps such as following:

A. at first fixedly exposure energy is constant, and setting the exposure bench mid-focal length is different numerical value, carries out photoetching process, and the figure after the photoetching is carried out cross-section analysis, measures ADI CD.

B. carry out etch process then, the figure after the etching is carried out cross-section analysis, measure AEI CD.

C. the advanced technologies Control Server calculates etch bias according to the measured value of ADI CD and the measured value of AEI CD.

D. repeat above-mentioned steps, obtain the different etch bias of different exposure focal length correspondences, promptly obtain the linear relationship of following this exposure focal length and etch bias, and set up database.

According to the database of having set up, in the technology afterwards, can realize control automatically by the advanced technologies Control Server, specifically see also Fig. 2, the measured value of the measured value of ADI CD and AEI CD can be sent to the advanced technologies Control Server, the advanced technologies Control Server calculates automatically to obtain corresponding etch bias, automatically search database inquires the exposure focal length that mates with this etch bias then, and this focal length fed back to exposure bench, thereby the exposure focal length of exposure bench is controlled at ideal range with etch bias.

The invention provides a kind of preferred embodiment, at first set up the database of linear relationship between different exposure focal lengths and the etch bias.Keep exposure energy constant, choose different exposure focal lengths, this exposure focal length from-0.15 to 0.4, carry out photoetching process then, carry out cross-section analysis, measure ADICD according to the figure after the photoetching.Carry out etch process then, figure after the etching is carried out cross-section analysis, obtained the measured value of AEI CD, the advanced technologies server can calculate etch bias automatically according to the measured value of ADI CD measured value and AEI CD then, the gained data can be found out in table 2 and the table 3 from table 1.Obtain the mean value that obtains a plurality of etch bias at each exposure focal length at last, promptly obtained corresponding relation between exposure focal length shown in the table 4 and the etch bias, this corresponding relation just is stored in the advanced technologies server, forms a database.Can obtain as shown in Figure 3 linear relationship according to the data relationship between the table 4.

Table 1

Table 2

Table 3

Table 4

The exposure focal length	Etch bias mean value
The exposure focal length	Etch bias mean value	-0.15	0
-0.1	65.7	-0.15	0
-0.1	65.7	-0.05	77.876
0	80.8733	-0.05	77.876
0	80.8733	0.05	81.4483
0.1	86.1967	0.05	81.4483
0.1	86.1967	0.15	91.9471
0.2	94.2067	0.15	91.9471
0.2	94.2067	0.25	100.678
0.3	108.106	0.25	100.678
0.3	108.106	0.35	118.603
0.4	130.02	0.35	118.603

According to the database of having set up, the measured value of the measured value of ADI CD and AEI CD can be sent to advanced technologies control service, the advanced technologies Control Server can obtain actual etch bias, automatically Query Database inquires the exposure focal length that mates most with this actual etch bias then, and this focal length fed back to exposure bench, thereby the exposure focal length of exposure bench is controlled at ideal range with etch bias.The exposure focal length of mentioning in the preferred embodiment of the present invention of coupling is meant in the storehouse of fetching data and the pairing exposure focal length of the immediate etch bias mean value of the etch bias of reality.

In other embodiments of the invention, also can set up the database of etch bias mean value and exposure focal length corresponding relation, but directly set up the database of etch bias and exposure focal length relation.

The present invention sets up etch bias and the linear relationship of exposure between the focal length, effectively overcomes because exposure bench after operation a period of time, and the drift of exposure focal length causes final etch bias to exceed this defective of ideal range.The present invention is the monitoring etching deviation in real time, adjusts the exposure focal length in real time according to etch bias.Simple and the realization easily of the method for this control etch bias effectively provides production efficiency, and has reduced production cost.

Claims

1, a kind of method of controlling etch bias, etch bias are the differences of the big or small AEI CD of dielectric layer size after the big or small ADI CD of special pattern size after the photoetching and the etching; It is characterized in that: this method comprises sets up database steps and automatic controlled step, at first set up the database of the different etch bias of different exposure focal length correspondences, can carry out the step of automatic control then in actual process, this automatic controlled step comprises following substep:

2, a kind of method of controlling etch bias as claimed in claim 1, it is characterized in that: the described step of setting up database comprises following substep:

B2. carry out etch process then, and obtain AEI CD measured value;

3, a kind of method of controlling etch bias as claimed in claim 1 or 2, it is characterized in that: adopt the advanced technologies server to obtain measured value and the ADI CD measured value of ADI CD, and calculate etch bias, and find the exposure focal length that mates most according to the etch bias search database.

4, a kind of method of controlling etch bias as claimed in claim 1 or 2, it is characterized in that: exposure bench is connected with the advanced technologies server, the advanced technologies service search feeds back to exposure bench to the exposure focal length that mates most, and it is the exposure focal length that mates most that searches that exposure bench can be set its exposure focal length.